University of Hong Kong researchers said on Wednesday people suffering from depression run twice the mortality risk of those who don't as the illness increases their likelihood of being beset by various physical diseases.

That conclusion was reached by the university's faculty of medicine team following an analysis of more than 260 studies involving more than 10 million patients and almost 2.8 billion control subjects across 27 countries and regions.

They found that depression may lead one to be susceptible to physical illnesses such as heart disease, diabetes, neurological disorders, endocrine diseases and cancer.

Age and gender factors may also affect such risks, the team said, with, for example, depressed women under the age of 25 running a mortality risk that is six times higher than peers who do not suffer from the mental illness.

The team also found those who are depressed also face a nearly 10-fold increased risk of suicide.

Professor Chang Wing-chung, who led the research and chairs the university’s department of psychiatry, said depression shares the same mechanism with other physical diseases.

“In fact, for people with depression, the mechanism is shared, no matter the genetics, and [that sharing takes in] also the physical mechanism [seen] with some of the chronic medical diseases, in terms of inflammation, increased immune abnormalities, so the shared abnormalities also cross over the physical and mental illness,” he said.

“That’s why they have increased risk of comorbid physical condition, leading to worse physical outcomes.”

Chang said those who suffer from depression often had to endure uncontrolled negative thoughts and a sense of hopelessness.

However, early treatment can reduce overall mortality risks despite uncertainties and immense stress at the time that diagnoses are made.

“Early detection is just the very first step," Chang said.

"Early detection, followed subsequently by appropriate and optimal treatment to maximise effectiveness is the key.

"The first period actually is the critical period, not just the diagnosis, but the very early stage of the development."

The team said patients taking antidepressants have their mortality risks lowered by about one fifth while those undergoing neurostimulation-based treatment can have such risks reduced by nearly one third.

Chang also pointed out that depression, just like physical illnesses, is highly treatable and people should seek help so as to receive the most appropriate treatment.

About 4 percent of the global population suffer from depression.